US5925276AExpiredUtility

Conductive polymer device with fuse capable of arc suppression

69
Assignee: RAYCHEM CORPPriority: Sep 8, 1989Filed: Jun 7, 1995Granted: Jul 20, 1999
Est. expirySep 8, 2009(expired)· nominal 20-yr term from priority
Inventors:Neville S. BatliwallaArthur F. EmmettBrian S. Larkin
H01C 7/027H05B 2203/02H05B 3/56H05B 3/146
69
PatentIndex Score
27
Cited by
65
References
24
Claims

Abstract

A melt-extrudable conductive polymer composition which contains a polymer, a particulate conductive filler, and a particulate nonconductive filler. When a standard strip heater is made from the composition and tested in a UL VW-1 test, it has comparable performance to a heater made from a second composition which is the same as the composition but which does not contain the nonconductive filler. When tested in a standard arcing fault test, the standard heater will trip a fuse in less time than is required by the second heater, i.e. in less than 30 seconds. In some embodiments, the composition also comprises a flame retardant, preferably a halogenated flame retardant. When strip heaters prepared from these compositions are tested in a standard arc propagation test, an arc will not propagate. A preferred nonconductive filler is Sb2O3.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. A strip heater circuit which comprises (1) a strip heater which comprises (a) a resistive element which is composed of a conductive polymer composition which comprises (i) a polymer,   (ii) a particulate conductive filler,   (iii) a particulate nonconductive filler, and   (iv) a flame retardant, and     (b) two elongate wire electrodes which can be connected to a source of electrical power to cause current to flow through the resistive element,     (2) a power supply electrically connected to the strip heater, and   (3) a first fuse which (a) is a very fast acting fuse, and   (b) is electrically connected to the strip heater and the power supply, wherein the heater is such that when tested in a standard arc propagation test, it will not propagate an arc.       
     
     
       2. A strip heater circuit according to claim 1 wherein the first fuse is part of a fused plug assembly. 
     
     
       3. A circuit according to claim 1 wherein the first fuse is an independent component in the circuit. 
     
     
       4. A circuit according to claim 1 wherein the circuit further comprises a resistor, a thermostat, a circuit protection device, or a indicating light electrically connected to the strip heater, the power supply and the first fuse. 
     
     
       5. A circuit according to claim 1 wherein the conductive filler comprises carbon black. 
     
     
       6. A circuit according to claim 1 wherein the nonconductive filler comprises an inorganic oxide. 
     
     
       7. A circuit according to claim 6 wherein the inorganic oxide comprises Sb 2  O 3 . 
     
     
       8. A strip heater assembly which comprises (A) a strip heater which comprises (1) a resistive element which is composed of a first conductive polymer composition which comprises (a) a polymer,   (b) a particulate conductive filler, and   (c) a particulate nonconductive filler, and     (2) two elongate metal electrodes which can be connected to a source of electrical power to cause current to flow through the resistive element, and     (B) a first fuse which (a) is a very fast acting fuse, and   (b) is electrically connected to the strip heater, the particulate nonconductive filler being such that when the first composition is made into a standard strip heater I and the standard heater I is tested in a standard arcing fault test in a circuit comprising a second fuse which is a very fast acting 10 A, 120/250V fuse, it trips the second fuse in less than 30 seconds.       
     
     
       9. An assembly according to claim 8 wherein the first fuse is connected between the two electrodes. 
     
     
       10. An assembly according to claim 8 wherein the first fuse is part of a fused plug assembly. 
     
     
       11. A strip heater circuit which comprises (1) a strip heater which comprises (a) a resistive element which is composed of a conductive polymer composition which comprises (i) a polymer,   (ii) a particulate conductive filler, and   (iii) a particulate nonconductive filler, and     (b) two elongate wire electrodes which can be connected to a source of electrical power to cause current to flow through the resistive element,     (2) a power supply electrically connected to the strip heater, and   (3) a first fuse which (a) is a very fast acting fuse, and   (b) is electrically connected to the strip heater and the power supply, wherein the particulate nonconductive filler is such that when the composition is made into a standard strip heater I and the standard strip heater I is tested in a standard arcing fault test in a circuit comprising a second fuse which is a very fast acting 10 A, 120/250V fuse, it trips the second fuse in less than 30 seconds.       
     
     
       12. A strip heater circuit according to claim 11 wherein the first fuse is part of a fused plug assembly. 
     
     
       13. A circuit according to claim 11 wherein the first fuse is an independent component in the circuit. 
     
     
       14. A circuit according to claim 11 wherein the circuit further comprises a resistor, a thermostat, a circuit protection device, or a indicating light electrically connected to the strip heater, the power supply and the first fuse. 
     
     
       15. A circuit according to claim 11 wherein the conductive filler comprises carbon black. 
     
     
       16. A circuit according to claim 11 wherein the nonconductive filler comprises an inorganic oxide. 
     
     
       17. A circuit according to claim 16 wherein the inorganic oxide comprises Sb 2  O 3 . 
     
     
       18. A strip heater circuit which comprises (1) a strip heater which comprises (a) a resistive element which is composed of a conductive polymer composition which comprises (i) a polymer,   (ii) a particulate conductive filler,   (iii) a particulate nonconductive filler, and   (iv) a flame retardant, and     (b) two elongate wire electrodes which can be connected to a source of electrical power to cause current to flow through the resistive element,     (2) a power supply electrically connected to the strip heater, and   (3) a first fuse which (a) is a very fast acting fuse, and   (b) is electrically connected to the strip heater and the power supply, wherein the conductive polymer composition is such that when it is made into a standard strip heater II and the standard strip heater II is tested in a standard arc propagation test, an arc will not propagate.       
     
     
       19. A strip heater circuit according to claim 18 wherein the first fuse is part of a fused plug assembly. 
     
     
       20. A circuit according to claim 18 wherein the first fuse is an independent component in the circuit. 
     
     
       21. A circuit according to claim 18 wherein the circuit further comprises a resistor, a thermostat, a circuit protection device, or a indicating light electrically connected to the strip heater, the power supply and the first fuse. 
     
     
       22. A circuit according to claim 18 wherein the conductive filler comprises carbon black. 
     
     
       23. A circuit according to claim 18 wherein the nonconductive filler comprises an inorganic oxide. 
     
     
       24. A circuit according to claim 23 wherein the inorganic oxide comprises Sb 2  O 3 .

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